Strengths of Acids and Bases Making Dilutions

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Slide 1

Chapter 9 Acids and Bases

Strengths of Acids and Bases

Making Dilutions

Slide 2

Strengths of Acids and Bases

Strong acids completely ionize (100%) in aqueous solutions

HCl + H2O H3O+ + Cl- (100 % ions)

Strong bases completely (100%) dissociate into ions in aqueous solutions.

NaOH Na+ (aq) + OH-(aq)

(100 % ions)

Slide 3

NH3, A Bronsted-Lowry Base

When NH3 reacts with water, most of the reactants remain dissolved as molecules, but a few NH3 reacts with water to form NH4+ and hydroxide ion.

NH3 + H2O NH4+(aq) + OH- (aq)

acceptor donor

+ +

Slide 4

Strong and Weak Acids and Bases

Strong acids

HCl, HNO3 , H2SO4

Most other acids are weak.

Strong bases

NaOH, KOH, and Ca(OH)2

Most other bases are weak.

Slide 5

Learning Check SW1

Identify each of the following as a

1) strong acid or base 2) weak acid

3) weak base

A. _ HCl (aq)

B. _ NH3(aq)

C. _ NaOH (aq)

D. _ H2CO3 (aq)

Slide 6

Solution SW1

Identify each of the following as a

1) strong acid or base 2) weak acid

3) weak base

A. _1 HCl (aq)

B. _3 NH3(aq)

C. _1 NaOH (aq)

D. _2 H2CO3 (aq)

Slide 7

Antacids

Used to neutralize stomach acid (HCl)

Many contain one or more weak bases

Alka-Seltzer: NaHCO3, citric acid, and aspirin

Di-gel: CaCO3 and Mg(OH)2

Gelusil: Al(OH)3 and Mg(OH)2

Maalox: Al(OH)3 and Mg(OH)2

Mylanta: Al(OH)3 and Mg(OH)2

Slide 8

More Antacids

Milk of Magnesia: Mg(OH)2

Rolaids: AlNa(OH)2CO3

aluminum sodium dihydroxy carbonate

Tums: CaCO3

Tempo: CaCO3, Al(OH)3, Mg(OH)2

Slide 9

Dilutions

Add water

Volume increases.

New concentration is less than initial

Slide 10

Concentration of A Diluted Solution

A 25 mL sample of a 6.0 M KOH is diluted by adding 75 mL of water. Calculate the new concentration of the KOH solution.

Moles KOH = 0.025 L x 6.0 moles = 0.15 moles

1 L

New volume = 25 mL + 75 mL = 100. mL = 0.100 L